The invention relates to a method and apparatus for calculating the green light duration in traffic-dependently controllable street traffic signal systems utilizing time intervals.
In accordance with the prior art, it is known to utilize time intervals to calculate the green light time interval between two vehicles following one another, utilizing vehicle detectors, and to compare the results with a theoretical time-limiting value. If this theoretical time-limiting value is exceeded, a switching order is issued to the traffic signal control system to terminate the green light duration. Some motorists, however, maintain an unnecessarily large distance behind the car ahead, and thus conventional systems, in spite of a normal flow of traffic, result in green light period being prematurely terminated even though a large number of vehicles may still be approaching an intersection. Working within the confines of adjustable parameters in prior art systems, this problem could be counteracted only by an impermissible long time interval whereby the disconnection of the green light period no longer could be regulated with a suitable degree of sensitivity.